Bipartite tubular molded synthetic resin furniture part with internal reinforcement

ABSTRACT

A bipartite generally tubular molded synthetic resin furniture part, such as a leg for a chair or table or a chair back assembly. The furniture part is composed of two complementary molded synthetic resin tube sections arranged side by side and having mating longitudinal marginal portions bonded to one another so as to define a cavity extending longitudinally through the part. One or both of the tube sections are provided with integral molded synthetic resin reinforcing formations, such as reinforcing ribs or flanges, which extend across the cavity at intervals and are bonded to the opposite tube section in such a way as to reinforce the part against deformation under the load. Additional reinforcement of the part may be provided by a metal rod positioned longitudinally within the cavity and extending through aligned openings in the reinforcing ribs.

United States Patent Anderson [54] BIPARTITE TUBULAR MOLDED SYNTHETICRESIN FURNITURE PART WITH INTERNAL REINFORCEMENT [72] Inventor: VictorF. Anderson, Wenonah, NJ.

' [73] Assignee: Shell Oil Company, New York, NY.

[22] Filed: June 4, 1970 [2]] Appl. No.: 43,521

Related U.S. Application Data [63] Continuation-impart of Ser. No.797,616, Feb.

7, 1969, abandoned.

[52] U.S. Cl ..52/731, 297/452 1 1 Oct. 17, 1972 FOREIGN PATENTS ORAPPLICATIONS 700,027 H1966 Italy ..52/730 Primary Examiner-Frank L.Abbott Assistant Examiner-James L. Ridlgill, Jr. Attorney-Beehler andArant and Martin S. Baer [57] ABSTRACT A bipartite generally tubularmolded synthetic resin furniture part, such as a leg for a chair ortable or a chair back assembly. The furniture part is composed of twocomplementary molded synthetic resin tube sections arranged side by sideand having mating 1ongitudinal marginal portions bonded to one anotherso as to define a cavity extending longitudinally through the part. Oneor both of the tube sections are provided with integral molded syntheticresin reinforcing formations, such as reinforcing ribs or fllanges,which extend across the cavity at intervals and are bonded to theopposite tube section in such a way as to reinforce the part againstdeformation under the load. Additional reinforcement of the part may beprovided by a metal rod positioned longitudinally within the cavity andextending through aligned openings in the reinforcing ribs.

4 Claims, 32 Drawing Figures PAIENTED BI 17 I 2 3.698.150

sum 1 OF 6 INVENTOR. V/cro/e 54/105250 o I NVEN TOR f 106702 'A/vpeso/vI 5M i W A T oeA/fyf PATENTEDncmmz 3.698.150

saw u UF 6 'g gg m REFERENCE TO COPENDING APPLICATION The presentapplication is a continuation-in-part of my copending application Ser.No. 797,616, filed Feb. 7, 1969 now abandoned.

Reference is also made herein to my application Ser. No. 677,153, filedOct. 23, 1967, and entitled PREFABRICATED PLASTIC CHAIR AND AS- SEMBLYMETHOD, now US. Pat. No. 3,455,605.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

This invention relates generally to the field of synthetic resinfurniture and more particularly to a ho]- low molded synthetic resinpartfor such furniture.

2. Description of the Prior Art:

Recent developments in synthetic resin material and synthetic resinmolding techniques have made possible the mass production of syntheticresin furniture which is practical, aesthetically pleasing, andpresently favored by ever increasing popularity and demand. A primaryadvantage of synthetic resin furniture over conventional woodenfurniture, of course, resides in the fact that virtually any furniturestyle, from the very simple to the highly ornate, may be mass producedat relatively low cost. Moreover, the coloring and surface texture ofsynthetic resin furniture may be readily varied to simulate virtuallyany furniture wood and surface finish.

Generally speaking, the mass production ofan article of furnitureinvolves two basic operations. These are fabrication of the variousparts of the article and assembly of the parts into a unitary furniturestructure. The present invention isconcerned with the fabrication ofcertain synthetic resin furniture parts which may be assembled withother parts to provide a completed article of furniture. As will becomeevident from the ensuing description, the invention may be embodied invarious kinds of furniture parts. However, the invention is concernedprimarily with and will be disclosed in relation to synthetic resinparts for chairs and tables, such as chair and table legs and chair backassemblies.

SUMMARY OF THE INVENTION According to its broader aspects, the inventionprovides a reinforced generally tubular synthetic resin furniture partcomprising a pair of complementary molded tube sections; at least one ofsaid tube sections having a generally U-shaped cross section, the legsand the web portion being of generally equal wall thicknesses as is theweb portion of the other of said tube sections; predetermined surfaceson each of the tube sections for providing permanent connection betweensaid tube sections; and means integral with at least one of said tubesections extending across the cavity between the tube sections forreinforcing said tube sections. The sections are joined to one anotherin any convenient way, as by adhesively bonding, solvent welding, orultrasonically welding the predetermined surfaces. The predeterminedsurfaces of the tube sections are shaped to mate in such a way that thejoints between the tube sections are virtually invisible, except perhapsby extremely close inspection. When thus assembled, the tube sectionsdefine a cavity extending longitudinally through the furniture part andbounded by inner wall surfaces of the tube sections. The exterior wallsurfaces of the tube sections may be ornately contoured and/or embossedto simulate any desired furniture style, sur face finish, or surfacetexture. The color of the synthetic resin material from which the tubesections 0 are molded may be selected to simulate any furniture wood andfinish.

An important feature of the invention resides in novel reinforcing meansfor reinforcing the furniture parts against deformation under load. Thisreinforcing feature permits reduction of the wall thickness of themolded synthetic resin tube sections and thereby enables production, atminimum cost, of furniture parts conforming to virtually any furniturestyle. According to this feature of the invention, one or both tubesections are integrally formed or molded with reinforcing formations,such as reinforcing ribs or flanges, which project from the inner wallsurfaces of the respective sections across the longitudinal cavitydefined by the tube sections, to the inner wall surfaces of the oppositesection. The contacting surfaces of the reinforcing formations and tubesections are bonded to one another in such a way that the completedfurniture part possesses great strength in spite of its hollow thinwalled construction.

A variety of reinforcing configurations are disclosed. In certaindisclosed embodiments, the reinforcing formations comprise ribs whichare disposed in planes transverse to and spaced along the longitudinalaxis of the part. In one of these embodiments, the reinforcing action ofthe ribs is aided by a metal rod which extends through openings in theribs. Other disclosed embodiments of the invention utilize reinforcingflanges disposed in longitudinal planes of the furniture part.

As noted earlier, the invention may be embodied in various types offurniture parts. The particular inventive embodiments disclosed hereinare chair and table legs. One disclosed embodiment is an entire backassembly for a chair including two rear legs and a back rest.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of aplastic chair embodying molded synthetic resin furniture parts accordingto the invention which, in this instance, are the front chair legs andthe chair back;

FIG. 2 is an enlarged sectionthrough one of the front chair legs takenon line 2--2 in FIG. 1;

FIG. 3 is an exploded fragmentary perspective view of the front chairleg;

FIG. 4 is an enlarged section through the chair back taken on line 4-4in FIG. 1;

FIG. 5a is an enlarged section through one of the rear chair legs takenon line 5a 5a of FIG. 1;

FIG. 5b is a section taken on line 5b-Sb of FIG. 1;

FIG. 6 is a fragmentary exploded perspective view of a modified moldedsynthetic resin furniture part according to the invention;

FIG. 6a is an enlarged sectional view of the embodiment shown in FIG.6',

FIG. 6b is an enlarged sectional view of the predetermined surfaces tobe connected shown in FIG. 6;

FIG. 7 is a fragmentary exploded perspective view of a further modifiedmolded synthetic resin furniture part according to the invention;

FIG. 7a is an enlarged sectional view of the embodiment shown in FIG. 7;

FIG. 8 is a fragmentary exploded perspective view of a further modifiedmolded synthetic resin furniture part according to the invention;

FIGS. 9 through 11 illustrate the manner of assembling the two sectionsof the furniture part illustrated in FIG. 8;

FIG. 12 is a fragmentary exploded perspective view of a further modifiedmolded synthetic resin furniture part according to the invention;

FIG. 13 is a section through the assembled furniture part of FIG. 12;

FIG. 14 is a fragmentary perspective view of a synthetic resin tableembodying molded synthetic resin furniture parts according to theinvention which, in this instance, are the table legs;

FIG. 15 is an enlarged side elevation of one of the table legs;

FIG. 16 is an enlarged section taken on line 1616 in FIG. 15;

FIG. 17 is an exploded fragmentary perspective view of the upper end ofthe table leg illustrated in FIG. 15;

FIG. 18 is a section taken on line 18-18 ofFIG.15;

FIG. 19 is a perspective view of a further modified molded syntheticresin furniture part or leg according to the invention;

FIG. 20 is an exploded perspective view of the leg illustrated in FIG.19;

FIG. 21 is an upper end view of the furniture leg illustrated in FIG.19;

FIG. 22 is a perspective view of a further modified molded syntheticresin furniture part or leg according to the invention;

FIG. 23 is an upper end view of the leg illustrated in FIG. 22;

FIG. 24 is an exploded perspective view of the leg illustrated in FIG.22;

FIG. 25 is an exploded fragmentary perspective view of a furthermodified molded synthetic resin furniture part or leg according to theinvention embodying a central reinforcing rod;

FIG. 26 is an exploded upper end view of the furniture leg illustratedin FIG. 25;

FIG. 27 is an upper end view of the assembled furniture leg of FIG. 25;and

FIG. 27a is an enlarged fragmentary section taken on line 27a-27a inFIG. 27.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1through b of these drawings, there is illustrated a synthetic resinchair l0 embodying molded plastic parts 12 and 14 according to theinvention. In this instance, parts 12 are the front chair legs and part14 is the back assembly for the chair. The front legs and back assemblyare attached to the front corners and rear side, respectively, of amolded plastic seat frame 16. This seat frame carries a seat cushion 18.Front legs 12 and back assembly 14 may be attached to the seat frame inany convenient way. One manner of affecting this attachment is disclosedin the aforementioned US. Pat. No. 3,455,605. According to thedisclosure of the latter patent, attachment of the legs and back to theseat frame is accomplished by providing the legs and back with integralmolded lug formations which fit snugly within complementary slots in theseat frame and are bonded to the frame.

The front chair legs 12 are mirror images of one another and eachcomprises a pair of relatively thin walled complementary synthetic resintube sections 20 and 22. These tube sections are arranged side by sideand have mating longitudinal marginal portions 24 disposed in mutualcontact and joined in any convenient way. By way of example, thecontacting margins 24 of the tube sections may be solvent welded. Thetube sections 20, 22 define a cavity 26, FIG. 2, extendinglongitudinally through the part and bounded by inner wall surfaces 28 ofthe tube sections. The tube sections have exterior wall surfaces 30which may be contoured and/or embossed to simulate various furniturestyles. In this instance, the exterior wall surfaces of the tubesections are shaped to simulate a simple tapered furniture leg.

In the particular chair leg configuration under discussion, the tubesections 20, 22 have similar, generally channel shapes in transversecross-section. Each tube section includes two leg portions, a side wallmember 32 and a flange 34 disposed in spaced parallel longitudinalplanes of the leg and a web portion 36 ex tending between and integrallyjoining the wall member and flange. The side wall member 32 of each tubesection is flush with its adjacent edge of the web portion 36. Theopposite edge of the web portion projects beyond the flange 34 adistance approximating the thickness of the side wall member to providea longitudinal ledge or shoulder 38 on each tube section. As shown, thetube sections 20, 22 of each leg are assembled in such a way that theside wall members 32 of each section abut the shoulder 38 on theopposite section and overlap, in face to face contact, the flange 34 onthe opposite section.

As noted earlier, a feature of the invention is concerned withreinforcement of the present furniture part or leg to enable the latterto have an economical hollow thin walled molded synthetic resinconstruction and yet possess sufficient strength and rigidity to resistdeformation under load. In the particular inventive embodiment underdiscussion, the side wall members 32 and web portions 36 of the tubesections 20, 22 provide the main body of the leg and the tube sectionflanges 34 effectively serve as reinforcing formations or flanges. Thelongitudinal edge of each flange fits snugly into a groove 40 in theinner wall surface of the opposite tube section. This groove of eachtube section is defined by its side wall member 32 and a longitudinalrib 42 projecting from the inner wall surface of the tube section inspaced parallel relation to the wall member. It will be observed thatthese interfitting flange and groove configurations serve to positivelylocate the tube sections laterally relative to one another.

As has been mentioned earlier, the tube sections 20 and 22 may be joinedby a convenient joining technique, such as solvent welding. It is alsoto be understood that other forms of joining may be used, such asultrasonic welding, inert gas welding, or hot stacking, depending uponthe particular cross-sectional configuration used for the furniture leg,as will be discussed in more detail hereinbelow. The cross sectionillustrated in FIGS. 2, 3, 4, and 5 are uniquely designed for beingjoined by solvent welding. In solvent welding certain nonvisiblesurfaces are wetted with a solvent which is highly active with aparticular synthetic resin material to be joined. The solvent actuallydissolves a portion of the synthetic resin on the joint surfaces. Whenthe wetted, partially dissolved surfaces come together, mixing of thesurfaces occur combining the synthetic resin .of one part to that of theother. After predetermined contact pressure has been applied along thejoint and a precalculated curing time allowed, a fixed joint will beachieved that approaches 100 per cent of the strength of the partmaterial.

For example, referring to FIG. 3, surface 24 of flange 34 of tubesection 22 is wetted as is the surface 24" of the side wall member 32 ofthe tube section 22. In addition, the surfaces defining the groove 40are also coated as are the extended edges of both the flange and theside wall member. In a like fashion, the corresponding members of thetube section are also coated and two tube sections 20 and 22 are broughttogether to cause a permanent joint so as to form a configuration asshown in FIG. 2. In order to provide room for synthetic resin materialwhich may be squeezed during the time that pressure is applied, the sidewall member 32 on each of the two sections is made slightly shorter thanthe flanges 34 so that when pressure is applied there is a flowing ofthe synthetic resin material to fill the slight gap provided between theends of the side wall members and the shoulders 38. This gap will becomefilled during the process which forms the unitary furniture part.Because of the substantial surface areas of the tube sections inabutment which become bonded, the resultant furniture part is a highstrength but economical element. It is, of course, understood that thecross sections shown in FIGS. 2, 4, and 5 will not have distinctboundary lines but rather tend to form a unitary piece without a clearindication of where the tube section 20 ends andwhere the tube section22 begins; nevertheless, for purposes of clarity, the cross-sectionaldrawings are made with distinct boundaries.

The rear molded plastic furniture part or chair back assembly 14comprises two complementary molded synthetic resin back sections 44 and46, FIGS. 1, 4, 5a, and 5b, arranged side by side. These complementaryback sections include lower tube sections 48 and 50, FIGS. 5a and 5b,which form rear chair legs 51, upper generally annular tube sections 52and 54, FIG. 4, which form a back rest frame 55, and an ornamentalinsert 56 within and joined to the frame to provide with the frame aback rest. Insert 56 has a cross section like that shown in FIG. 2.Referring to FIGS. 4 5b, it will be seen that the chair back tubesections 48, 50,52, 54 are similar in transverse cross section to thetube sections 20, 22 of the front chair legs 12 and mate in the samemanner as the latter legs. Accordingly, it is unnecessary to re-describethe back tube sections in detail. Suffice it to say that these back tubesections are secured to one another in the same manner as the front legtube sections so as to join the back sections 44, 46 into a unitarychair back structure. The ornamental insert 56 of the chair back may beseparatelyformed and secured in place within the chair back frame.Alternatively, this insert may be molded in one piece, integral with oneof the chair back sections, or in two mating portions integral with thetwo chair back sections, as desired.

FIGS. 6 13 illustrate various alternative molded synthetic resinconfigurations according to the invention which may be employed in thefront chair legs 12 and/or the chair assembly back 14 of FIG. 1. Themolded synthetic resin furniture part of FIG. 6 comprises a pair ofcomplementary molded plastic tube sections in the form of a channelsection 102 and a cap strip section 104. The channel section 102 hasparallel side walls 106 integrally joined along one longitudinal edge bythe web portion 108. The two side walls 106 have grooves 109 and 110formed in the ends thereof which mate with projections 111 and 112,respectively, of the cap strip section 104. As more clearly illustratedin FIG. 6b, the projection 112 is purposely made longer and narrowerthan the groove 110. In addition, surfaces 112" and 110" are slightlyoblique so as to provide a V-shaped groove. The groove will be locatedon the in side of the furniture part. The greater length of theprojection 112 insures intimate contact of the tube sections and thereis sufficient room for the flow of excess material with squeeze outbeing directed to the groove on the inside of the furniture part so asto retain an unmarred outer surface.

While any suitable joining technique may be used for the configurationshown in FIG. 6, it has been especially designed for ultrasonic welding.This welding technique is accomplished through the use of high frequencyvibrations between two parts of similar material; the high frequencyvibration is controlled and transmitted through a special transducerhead cone, the size, shape, type, and location of which control thefinished weld. The degree of synthetic resin melt is achieved as aresult of the frequency of vibration and the thickness of the partsbeing connected. The parts must be maintained in intimate and accuratecontact throughout the welding operation to effect a good bond. Asmentioned, the additional space created by thegroove 110 allows themelted material to flow in a predetermined manner during the weldingoperation so that after the joining technique is finished a bondedconnection is made, such as shown in FIG. 6a and the second part of FIG.6b.

Furniture part 100 is provided with internal reinforcing formations 114which extend across the cavity 116 within the part. In this instance,the reinforcing formations comprise an integral molded plasticreinforcing rib or flange 118 of generally zig-zag shape which projectsfrom the inner wall surfaces of the cap strip section 104, andtransverse reinforcing ribs 120 integral with and extending laterally ofthe reinforcing flange within each of the interior angles defined by theflange. Ribs 120 are disposed in planes normal to and spaced along thelongitudinal axis of the furniture part.

The reinforcing flange 118 and ribs 120 are so dimensioned that when thechannel and cap strip tube sections 102, 104 are assembled, thereinforcing flange and ribs fit snugly between the channel section sidewalls 106 and abut the inner wall surface of the channel section webportion 108. To achieve additional strength, the contacting surfaces ofthe reinforcing flange and ribs and the channel section may be bonded toone another to form a rigid synthetic resin furniture part. Bonding maybe accomplished by ultrasonic welding or solvent welding techniques.

The synthetic furniture part 200 of FIG. 7 is similar to that of FIG. 6in that part 200 has a pair of molded synthetic resin tube sections inthe form of a channel section 202 and a cap strip section 204,respectively. Channel section 202 has parallel side walls 206 integrallyjoined along one longitudinal edge by a web portion 208. Cap stripsection 204 is laterally dimensioned to seat against the oppositelongitudinal edges of the channel side walls 206 so as to close the openside of the channel section. The lateral edges 205 and 207 of the capstrip section 204 are oblique as are the extended edges 201 and 203 ofthe side walls 206. When brought together, the channel section 202 andcap strip section 204 form lateral longitudinally extending grooveswhich are uniquely designed for still another joining technique than thetwo already mentioned. For example, the FIG. 7 embodiment may bepermanently connected by an inert gas welding technique. Inert gaswelding is quite similar to conventional metal welding in that asynthetic resin welding rod of the same material that is to be joined islaid within the two lateral grooves and is melted. Neither the rod northe part to be welded are totally melted; only a shallow section of therod and the part surfaces reach the melting temperature. It is thecontact pressure of the rods outer surface that causes the contactbetween theparts and the rod. Thus, prior to welding a configuration asshown in FIG. 70 will exist, and after welding and finishing the outersurface of the side walls will be completely flush, providing anaesthetically beautiful furniture part.

Plastic furniture part 200 is provided with reinforcing formations 210.In this instance, the reinforcing formations comprise reinforcingflanges 212 integrally molded on the inner wall surface of the cap stripsection 204. Flanges 212 are disposed in spaced longitudinal planes ofthe part parallel to the side walls 206 of the channel section 202.These flanges project across the central cavity 214 in the part intocontact with the inner wall surface of the web portion 208 of thechannel section. Formed in the inner wall surface of the web portion,are longitudinal grooves 216 which snugly receive the longitudinal edgesof the reinforcing flanges. The contacting surfaces of the reinforcingflanges and channel web portion may be bonded to one another to providea strong, rigid synthetic resin furniture part.

Turning now to FIGS. 8 11, the illustrated synthetic resin furniturepart 300 comprises molded synthetic resin channel and cap strip tubesections 302, 304 which are similar to those of FIG. 6. Part 300 hasreinforcing formations 306 in the form of separate reinforcing ribs 308which are integrally molded on the inner wall surface of the cap stripsection 304. These reinforcing ribs are disposed in planes normal to anduniformly spaced along the axis of the central cavity 310 through thepart 300. Reinforcing ribs 308 are dimensioned to fit snugly between theside walls 312 of the channel tube sections 302 and to seat against theinner wall surface of the channel web portion 314.

In this particular embodiment, attachment of the channel and cap stripsections is provided by synthetic resin rivet posts 316 which areintegrally molded on the inner wall surface of the channel web portion314 and terminate in rivet-like ends or tips 318. When the channel andcap strip sections are assembled, these rivet tips project throughexternally counter-sunk holes 320 in the cap strip section 304. Afterassembly of the-channel and cap strip sections, pressure and heat areapplied to the protruding rivet tips 318 so as to form a flushconfiguration, shown in FIG. 11.

As with the FIG. 7 embodiment, the extended ends of the side walls 312have oblique surfaces 313 and 315 while the lateral edges of the capstrip section 304 have oblique surfaces 301 and 303. However, unlike theFIG. 7 embodiment, the corresponding surfaces, such as 301 and 313,complement each other to form an abutment so that the surfaces 301 and313 lie in an oblique plane which intersects a corner of the finishedfurniture part. By being so constructed, the boundary line between thetwo sections become nearly invisible. Additionally, the surfaces, suchas 301 and 313, may be bonded to one another, such as by solventwelding, to additionally hold the two sections in rigid connection.

FIGS. 12 and 13 illustrate a modified synthetic furniture part 400according to the invention which is identical to the furniture part 300of FIGs. 8 11 with two exceptions. First, both the channel tube section402 and the cap strip tube section 404 of the part 400 are formed withreinforcing ribs 406. These ribs are arranged in alternate sequencyalong the axis of the cavity 408 through the furniture part. Secondly,the cap strip section 404 is provided with integral molded plasticsleeves 410 which project from the inner wall surface of the stripsection and receive rivet posts 412 on the channel section 402 when thesections are assembled. After assembly, the protruding tips 414 of therivet posts are deformed by the application of heat and pressure, in thesame manner as discussed in connection with the synthetic resinfurniture part of FIGS. 8 11.

Referring now to FIGS. 14 18, there is illustrated a further modifiedsynthetic resin furniture part according to the invention which, in thisinstance, is a leg 500 for a table 502. Leg 500 has two complementarymolded synthetic resin tube sections, a channel section 504 and a capstrip section 506 arranged side by side with mating longitudinalmarginal portions 508 of the sections in contact. As in the previousembodiments of the invention, the tube sections may be joined byadhesively bonding, inert gas welding, solvent welding, orultrasonically welding their contacting marginal surfaces. When thusassembled, the tube sections define a cavity 510 extendinglongitudinally through the leg. Integrally molded on the inner wallsurfaces of the tube sections are reinforcing ribs 512 which extendacross the cavity and seat against and which may be bonded to theopposite tube section, as before.

It will be observed that the channel section 504 has a generally channelshape in transverse cross section and the cap strip section 506 isessentially a cap strip which closes the upper side of the channelsection. From this standpoint, the table leg 500 is generally similar tothe furniture parts or chair legs described earlier. However, theexternal wall surfaces of the table leg are shaped to provide the legwith a French provincial design. As a consequence, the channel section504 has an arcuate cross section which varies along the leg from arelatively deep arcuate channel shape at the lower end of the leg to arelatively shallow arcuate channel shape at the upper end of the leg.The cap strip section 506 also has an arcuate cross section which variesalong the leg from an externally convex shape at the lower end of theleg to an externally concave shape at the upper end of the leg.

In the particular table leg illustrated, the mating longitudinalmarginal portions 508 of the channel and cap strip sections 504, 506comprise laterally thickened wall portions 514 on the channel section,along its longitudinal edges. These thickened wall portions formrecesses 516. The recesses 516 receive mating longitudinal beads ortongues 518 which are integrally molded on the cap strip section alongits longitudinal margin. Referring to FIGS. 16 and 18, it will beobserved that the longitudinal marginal portions 508 of the tubesections mate or engage in a manner such that the external wall surfacesof the tube sections are flush with one another along the marginaljoints between the sections so as to render these joints virtuallyundiscernible, except perhaps by extremely close inspection.

Table 502 has a frame 520 to which the upper end of the table leg 500 isattached. This attachment may be accomplished in various ways. In theparticular embodiment shown, an insert 522 with threaded studs 524 iscontained within the upper end of the leg cavity 510. The studs 524protrude through holes (not shown) in the confronting upper portion ofthe cap strip section 506. As already noted, this upper portion of thecap strip section has an externally concave and hence an internallyconvex arcuate shape in transverse cross section. The upper portion ofthe channel section 504, on the other hand, has an externally convex andhence internally concave arcuate shape in transverse cross section. As aconsequence, the upper end of the leg cavity 510, which receives theinsert 522, has an arcuate cross section. The insert 522, which maycomprise a molded synthetic resin, foam synthetic resin, or filled woodpart, has the same arcuate shape in transverse cross section as the legcavity and thus complements the cavity. The inner concave surface 528 ofthe insert seats flush against the inner concave wall surface 530 of thecap strip section so as to provide extensive face to face contactbetween these parts.

The upper external concave wall surface 532 of the cap strip section 506seats flush against a mating side surface on the table frame 520 whenthe leg is assembled on the frame. The studs 524 of the leg insertextend through openings in the frame and receive nuts (not shown) whichare tightened against the inner sides of the frame to firmly attach theleg to the frame. In this regard, it will be understood that the face toface contact of the upper portion of the cap strip section 506 with thetable frame 520 and the leg insert 522 prevents deformation of the legwhen the nuts are tightened and thereby assures firm attachment of theleg to the frame. Referring to FIG. 17, it will be seen that the capstrip section is also enlarged to provide an upwardly presented shoulder536 just below its upper concave, table frame seating surface. Thisshoulder seats against the under side of the table frame to verticallysupport the frame and resist lateral rotation of the leg relative to theframe.

FIGS. 19 24 illustrate modified synthetic resin table legs 600 and 602according to the invention which are generally similar to the table leg500, just described. The table legs 600, 602 differ from the legs 500 inthat the external wall surfaces of the modified leg are shaped toconform to contemporary designs, rather than a French provincial design.Also, the fastening means for securing the modified legs to the tableframe comprise tapered attachments lugs 604 which are integrally moldedon the upper concave table frame seating surfaces 606 of the cap striptube sections 608, 609 of the legs. These lugs are adapted to fit snuglywithin mating tapered grooves in the table frame and to be force fittedor bonded to the frame. The leg tube sections have alternate reinforcingribs 610.

Turning now to FIGS. 25 27, there is illustrated a modified syntheticresin furniture leg 700 according to the invention which may beutilized, for example, as either a chair leg or a table leg. Thesynthetic resin furniture part or leg 700 comprises two complementarymolded synthetic resin tube sections 704, 706. In this instance, thetube sections are generally triangular in cross section and mate in sucha way as to provide a furniture leg of rectangular cross section. Theexternal wall surfaces of the tube sections are quite plain and providea leg of simple tapered configuration. It will be understood, of course,that the furniture leg 700 may have any cross-sectional shape andconform externally to any desired furniture style.

Projecting from the inner wall surfaces and beyond the confronting opensides of the tube sections 704, 706 are a number of integral moldedsynthetic resin reinforcing ribs 708. These ribs are disposed in planesnormal to and spaced along the longitudinal axis of the leg. When thetube sections 704, 706 are assembled, the ribs 708 project across thecavity 710 through the leg into contact with the opposite tube section.As in the previous embodiments of the invention, the tube sections arejoined to one another, as, for example, by bonding to one another themating longitudinal marginal portions of the tube sections and thecontacting inner wall surfaces of the sections and the reinforcing ribs.

The reinforcing ribs 708 of the tube sections 704, 706 alternate.Moreover, these ribs are spaced along the axis of the leg 700 in such away that when the tube sections are assembled, the corresponding ribs onthe sections overlap in face to face contact. Leg reinforcing means 702comprise a metal reinforcing rod 711 with end flanges or heads 712 whichis positioned longitudinally within the leg cavity 710 and extendsthrough aligned rib openings 714 in the reinforcing ribs 708. In thisinstance, the rib openings 714 comprise slots which open longitudinallythrough the outer edges of the ribs and overlap one another at theirclosed ends to effectively define a circular rod receiving opening. Asshown in FIG. 27a, the rod end flanges 712 project edgewise intolaterally opening grooves in the tube sections 704, 706, whereby the rodsupports a portion of the axial load on the furniture part. The rod thusreinforces the part axially as well as against bending. It will beunderstood that the open ended slot configuration of the reinforcing ribopenings 714 permits the tube sections 704, 706 to be assembled aboutthe reinforcing rod 702. In this latter connection, it will be observedthat in the particular inventive embodiment shown, as well as in all ofthe other disclosed inventive embodiments, the complementary tubesections are shaped to be brought into mating assembled engagement byrelative assembly movement of the sections along direction linestransverse to the length of the furniture part or leg. It would also bepossible to insert a series of filament fiber lines into the location ofthe rod 711 while under tension, thus increasing the load carryingstrength beyond a metal rod support.

In the particular furniture leg 700 selected for illustration in FIGS.25 27, normally inner or rear tube section 704 is formed with integralmolded synthetic lugs 716 to fit within and be bonded to mating groovesin the furniture frame 718 for attaching the leg to the frame. Thenormally outer or front tube section 706 has a V-shaped upper end 720which projects above the upper end of the tube section 704 and isadapted to fit about the corner of the frame in the manner shown.

What has been described more generally are furniture pieces or partsmade up of two tube sections which have predetermined surfaces which arebonded to achieve a unitary, rigid and strong furniture part. Asmentioned, there are several techniques for connecting the two tubesections together with unique designs favoring one or the other of thejoint techniques. The designer of a piece of furniture will choosewhichever technique and corresponding structure is most economical andsuitable for the particular style that he is concerned with.

In each embodiment of the invention, the cavity through the moldedsynthetic resin part may be filled with foam synthetic resin or otherfiller material similar to the insert 522, FIGS. 16 and 17, to providethe part with a solid sound and feel resembling a wood part.

It will be immediately evident to those versed in the art that a hollow,split molded synthetic resin furniture part according to the inventionhas numerous inherent advantages over a solid, one piece molded part.Among the foremost of these advantages are the following:

1. Individual parts will weigh substantially less.

2. lnitial part costs will be greatly reduced by reducing the amount ofmaterial used in and reducing the production cycle time (cycle timereduction is obviously due to quantity of material that must fill themold cavity and the time required for preliminary cooling).

3. Section modular strength is greater in a hollow cross section than asolid cross section.

4. There is less material wasted in a rejected part.

5. As part of the art of injection molding, equal wall thicknessproduces parts with a minimum of internal stresses developed during themolding operation and cooling.

6. Hollow parts will more closely equal the weight of wood.

7. Hollow parts will not warp as readily as thick solid sections.

8. lnjection molding equipment required to produce two piece hollowparts will need less mold clamp pressure and less pressure need tosqueeze the injecting synthetic resin into the mold.

The invention has been described in considerable detail in or er tocomply with t e patent laws by providing a ull public disclosure 0 atleast one of its forms. However, such detailed description is notintended in any way to limit the broad features or principles of theinvention, or the scope of patent monopoly to be granted.

1 claim:

1. A bipartite tubular molded synthetic resin furniture part withinternal reinforcement comprising:

a pair of complementary molded synthetic resin tube sections arrangedside by side and having mating longitudinal marginal portions disposedin mutual contact and bonded to one another to join said tube sectionsinto a unitary tube, said tube sections together defining a cavityextending longitudinally therethrough and bounded by interior wallsurfaces of said tube sections;

each of said tube sections including a plurality of integrally molded,plastic reinforcing ribs which project fromthe interior wall surface ofsaid tube section and extend across said cavity in planes generallyperpendicular to the longitudinal axis of said cavity, said plurality ofribs being spaced 7 along the length of said cavity and havingprojecting end edges which are seated against and bonded to the interiorwall surface of the other tube section;

the projecting ends of all of said ribs also having openings formedtherein which are aligned longitudinally of said cavity; and

a metal reinforcing rod extending longitudinally within said cavity andbeing received by all of said rib openings, the tube cooperativelyformed by said pair of tube sections also having interior end surfaceswhich are engaged by respective ends of said metal reinforcing rod;

whereby said reinforcing rod is effective to support a portion of anyaxial load placed upon said tube as well as reinforcing said tubeagainst bending.

2. A furniture part as claimed in claim 1 wherein said rib openingscomprise slots which open through the projecting end edge of each ofsaid ribs, whereby said tube sections may be assembled together aboutsaid reinforcing rod by placing all of said ribs into straddlingrelationship with said reinforcing rod.

3. A furniture part as claimed in claim 1 wherein the ribs on one tubesection alternate with the ribs on the other tube section.

4. A furniture part as claimed in claim 1 wherein each of said tubesections is generally triangular in cross-section, and said tubesections together form a tube of generally rectangular crosssection.

1. A bipartite tubular molded synthetic resin furniture part withinternal reinforcement comprising: a pair of complementary moldedsynthetic resin tube sections arranged side by side and having matinglongitudinal marginal portions disposed in mutual contact and bonded toone another to join said tube sections into a unitary tube, said tubesections together defining a cavity extending longitudinallytherethrough and bounded by interior wall surfaces of said tubesections; each of said tube sections including a plurality of integrallymolded, plastic reinforcing ribs which project from the interior wallsurface of said tube section and extend across said cavity in planesgenerally perpendicular to the longitudinal axis of said cavity, saidplurality of ribs being spaced along the length of said cavity andhaving projecting end edges which are seated against and bonded to theinterior wall surface of the other tube section; the projecting ends ofall of said ribs also having openings formed therein which are alignedlongitudinally of said cavity; and a metal reinforcing rod extendinglongitudinally within said cavity and being received by all of said ribopenings, the tube cooperatively formed by said pair of tube sectionsalso having interior end surfaces which are engaged by respective endsof said metal reinforcing rod; whereby saiD reinforcing rod is effectiveto support a portion of any axial load placed upon said tube as well asreinforcing said tube against bending.
 2. A furniture part as claimed inclaim 1 wherein said rib openings comprise slots which open through theprojecting end edge of each of said ribs, whereby said tube sections maybe assembled together about said reinforcing rod by placing all of saidribs into straddling relationship with said reinforcing rod.
 3. Afurniture part as claimed in claim 1 wherein the ribs on one tubesection alternate with the ribs on the other tube section.
 4. Afurniture part as claimed in claim 1 wherein each of said tube sectionsis generally triangular in cross-section, and said tube sectionstogether form a tube of generally rectangular cross-section.